Mycorrhizal fungi and heavy metal tolerance of fast growing reforestation tree species

Soil pollution due to high contamination of heavy metals is a very depressing issue in our environment. Different solutions were posed to minimize the heavy metal contamination in soil. One of these solutions is by means of phytoremediation - a process which uses green plants to clean contaminated soils. Compared to other methods, phytoremediation in association with mycorrhizal fungi poses an immediate solution at a cheaper cost. Rehabilitation and reforestation of heavy metal contaminated sites can significantly contribute in our country's economical, agricultural and ecological stability. Three fast growing tree species were used in the experiment namely: Acacia mangium, A. aulacocarpa and Swietenia macrophylla and inoculated with either Gigaspora margarita, Glomus etunicatum, a commercial mycorrhizal inoculant 'Mykovam' and mycorrhizal fungi from mine site coded as Paracale isolates. Mykovam is a soil inoculant comprising of G. margarita, G. etunicatum and G. macrocarpum whereas Paracale isolates were a mixture of Glomus, Entrophospora, Scutellospora and Acauiospora. The study was conducted to determine heavy metal tolerant fast growing reforestation tree species, and to determine the growth promoting and ameliorating effects of mycorrhiza in fast growing trees grown in mine waste soil. The experiment was one in a Randomized Complete Block Design with 10 replicates. Inoculated A mangium seedlings showed higher height and biomass than the uninoculated ones. Mycorrhizal A. aulacocarpa, showed higher height, biomass and phosphorus uptake than non-inoculated ones. Swietenia macrophylla seedlings were significantly affected in its height and biomass but the phosphorus content was higher than the non-mycorrhizal counterpart. Inoculation with mycorrhizal fungi enhanced the heavy metal tolerance of A. mangium, A. aulacocarpa and S. macrophylla and could be potential species for the rehabilitation and reforestation of heavy metal contaminated areas.